Anti-stalling motor fuel



United States Patent 3,256,074 ANTI-STALLING MOTOR FUE George W. Eckert, Wappingers Falls, N.Y., assignor to Texaco Inc., New York, N.Y., a corporation of Delaware No Drawing. Filed Nov. 13, 1962, Ser. No. 237,330 8 Claims. (CI. 44-71 This invention relates to a volatile gasoline composition of improved anti-stalling properties containing a salt of an alkenyl succinic acid and an alkylamine. More particularly, it involves the discovery that salts of an alkenyl succinic acid and of certain tertiary alkyl primary amines are effective anti-stalling, anti-icing additives for gasoline.

When internal combustion engines are operated on a gasoline fuel having the desired volatile characteristics for cold weather driving, a stalling problem is encountered during the warming period particularly under cool humid atmospheric conditions. It has generally been recognized that the cause of repeated engine stalling in cool humid weather is the formation of ice in the carburetor. Gasoline evaporation in the carburetor has a suflicient refrigerating effect to condense and freeze the moisture present in the air. Ice particles deposited on the metal surfaces of the carburetor partially or completely block the air passageway between the carburetor throat and the carburetor throttle valve with resulting stalling particularly when the engine is idling. The alkenyl succinic acid-amine salts are particularly useful in the highly volatile fuels which are particularly prone to engine stalling due to ice formation under cool humid conditions.

The gasoline and fuel composition of this invention comprises a substantial concentration of volatile components and about 0.0002 to 0.003 weight percent of a salt of an alkenyl succinic acid wherein the alkenyl group is C to C and a C to C tertiary alkyl primary amine, said salt containing a total of to 48 carbon atoms. The presence of an alkenyl succinic acid-amine salt of prescribed composition and in the prescribed concentration imparts excellent anti-icing and anti-stalling properties to the resulting gasoline compositions.

The effectiveness of the alkenyl succinic acid-amine salts of the invention particularly in the concentrations set forth was most surprising and unexpected. Generally it has been necessary to employ 10 to 12 pounds per thousand barrels of an anti-icing additive to produce a fuel having significantly effective anti-stalling properties. In view of this, an additive effective at 1.5 pounds per thousand barrels is exceptional. This discovery was all the more unexpected in that similar compounds employed in motor fuels at concentrations as much as 400 percent greater than the concentrations of the anti-icing additives of the invention were, nevertheless, ineffective anti-stalling agents.

The class of effective alkenyl succinic acid-amine salts have the following general formula:

' succinic acids are dibasic acids, the salts are obtained by mixing one mole of the acid with two moles of the amine.

"ice

The product salts having a total of 15 to 48 carbon atoms. a

- The alkenyl succinic acid component which can be employed in preparing the salts of the invention include those having a total of 7 to 28 carbon atoms. Mixtures of alkenyl succinic acids are also suitable. Typical effective acids include octenyl succinic acid, 2,3-dimethyl hexenyl succinic acid, 4-ethylhexenyl succinic acid, decenyl succinic acid, undecenyl succinic acid, hexadecenyl succinic acid and tetradecenyl succinic acid. The preferred alkenyl succinic acids have from 10 to 16 carbon atoms in the alkenyl group with dodecenyl succinic acid being particularly preferred. Dodecenyl succinic acid is generally prepared by alkylating maleic anhydride with propylene tetramer and hydrolyzing the'pr-oduct to the acid.

The alkylamines employed for preparing the salts of the invention are primary alkylamines in which the alkyl radical is a tertiary alkyl radical and in which the number of carbon atoms in said radical is from 4 to 10, preferably from 4 to 8. Mixtures of tertiary alkyl primary amines can also be employed to prepare the salts of the invention. Examples of effective amines are tertiary octylamine, tertiary butylamine, tertiary amylamine, tertiary hexylamine and tertiary decylamine.

Examples of outstandingly effective salts of the invention are those produced from the following mixtures: 1 mole of decenyl succinic acid and 2 moles of tertiary butylamine, 1 mole of dodecenyl succinic acid and 2 moles of tertiary butylamine, 1 mole of decenyl succinic acid (or of dodecenyl succinic acid) and 2 moles of tertiary hexylamine, 1 mole of decenyl succinic acid and 2 moles of tertiary octylamine and 1 mole of dodecenyl succinic acid and 2 moles of tertiary octylamine.

The alkenyl succinic acid-amine salts of this invention are effective as anti-stalling, anti-icing agents for motor fuels in concentrations of 0.0002 to 0.003 weight percent of the total motor fuel. The preferred concentration of the salt in a motor fuel is from 0.0005 to about 0.002 weight percent. Amounts above 0.003 weight percent are also effective but make no significant improvement in the properties of the motor fuel. Concentrations of 1.5 and 3.0 pounds of the salt per thousand barrels of gasoline, equivalent fro-concentrations of 0.006 and 0.0011 weight percent respectively and within the preferred range have proven particularly effective in forming fuels of excellent anti-stalling, anti-icing properties.

. The action of the alkenyl succinic acid-amine salts for their anti-stalling, anti-icing properties in motor fuels was evaluated in a carburetor icing demonstrator apparatus consisting of a vacuum pump adapted so that cool moisture saturated air from an ice tower is drawn through a simple glass tube gasoline carburetor. The gasoline sample is placed in a sample bottle and is drawn into a glass carburetor equipped with a 20 gauge hypodermic needle. Evaporation of the gasoline in the glass tube further cools the cold moist air with resulting ice formation on the throttle plate. The formation of ice on the throttle plate causes the engine to stall and it has been found that this condition is equivalent to a pressure drop across the throttle plate of about 0.5 inches of mercury. In the test, the time to reach 0.5 inches of mercury pressure is recorded. The vacuum pump is adjusted to give a vacuum of 1.8 inches of mercury and the test is run until a pressure of 2.3 inches of mercury has been reached or is run for 300 seconds. Since with mostfuels this pressure drop is reached in 1-4 minutes, 300 seconds is the maximum time for a run. A recording of 300 seconds indicates no stalling within'the test period. Each fuel is run 4 times in succession and the average is recorded. If the difference between the runs is great, the glass tube carburetor and the test throttle are washed Patented June 14, 1966 V with alcohol, flushed out with gasoline and the runs repeated. A leaded winter grade premium gasoline having a Reid vapor pressure of about 13 gives a stall in about 45-65 seconds in this test. Additives which raised the stall time to over 200 seconds are regarded as effective anti-stalling, anti-icing additives.

The base fuel employed to evaluate the eifectiveness of the alkenyl succinic acid-amine salts of this invention was a premium gasoline containing 3.0 cc. of TEL per gallon. This gasoline had an ASTM distillation IBP of 98 R, ER of 362 F. and a research octane rating of 100.0. Motor fuels containing the additives of the invention, the additive concentrations employed and the anti-stalling performance are listed in Table I below.

TABLE I.-MOTOR FUEL ANTI-STALLING TEST Cone, Stalling Additive Salt lbs. per Time,

1,000 Seconds bbls.

1. None; nu 71 2. 1 mole dodecenyl succinic acid: 2 moles tertiary butylamine 1. 5 206 3. 1 mole dodecenyl sn 2 moles tert y butylamine 3. 300+ 4. 1 mole dodecenyl succinic acid: 2moles tertiary octylamine 1. 5 300+ 5. 1 mole dodecenyl succinic acid: 2 moles te tiary octylamine 3. 0 300+ 6. 1 mole dodecenyl succinic acid: 2 moles Pr iene 7. 1 mole dodecenyl succinic acid: 2 moles Primene 8. 1 mole dodecenyl succinic acid: 2moles Primene 9. 1 mole dodecenyl succinic acid: 2 moles Primene JM-T 2 1. 5 88 10. 1 mole dodecenyl succinic acid: 2 moles Primene JM-T 2 3. 0 92 11. 1 mole dodecenyl succinic acid: 2 moles Prirnene J M-T 2 6. 0 113 Primene 81R=a tertiary alkyl primary aliphatic amine in which the aklyl chain is a. mixture of branched-chain isomers varying princlpally from 11-14 carbon atoms.

2 Prirnene J'MT=a tertiary alkyl primary aliphatic amine in which the alkyl chain is a mixture of branched-chain isomers varying principally trom 18 to 22 carbon atoms.

The foregoing data show the outstanding anti-stalling, anti-icing properties of the alkenyl succinic acid-amine salts of the invention. The additives of the invention having the prescribed number of carbon atoms in the molecule significantly improved the anti-stalling properties of the base fuel from a level of about 70 seconds to substantially over 200 seconds or more to stall. As indicated previously, a good anti-stalling, anti-icing additive should improve the properties of the base fuel to such an extent that no stall is noted in 200 seconds.

I claim:

1. A gasoline containing 0.0002 to 0.003 weight percent of a diamine salt of an alkenyl succinic acid wherein the alkenyl group is C to C and a C to C primary alkylamine in which said alkyl radical is a tertiary hydrocarbyl radical, said salt containing a total of 15 to 48 carbon atoms, and imparting improved anti-stalling, antiicing properties to said gasoline.

2. A gasoline according to claim 1 in which said alkenyl succinic acid-diamine salt is present in a concentration of about 0.0005 to 0.002 weight percent.

3. A gasoline motor fuel containing 0.0002 to 0.003-

weight percent of an alkenyl succinic acid-amine salt having the formula:

| (R'NHz)z-HOCOCH1CHCOOH wherein R" is an alkenyl radical containing 3 to 24 car-' bon atoms and R is a tertiary aliphatic hydrocarbyl radical containing 4 to 10 carbon atoms, said salt containing a total of 15 to 48 carbon atoms and imparting improved anti-stalling, anti-icing properties to said motor fuel.

4. A gasoline containing 0.0002 to 0.003 weight percent of a diamine salt of an alkenyl succinic acid wherein the alkenyl group is C to C and tertiary butylamine.

5. A gasoline containing 0.0002 to 0.003 weight percent of a diamine salt of an alkenyl succinic acid wherein the alkenyl group is C to C and tertiary octylamine.

6. A gasoline containing 0.0002 to 0.003 weight percent of a diamine salt of dodecenyl succinic acid and a C to C primary alkylamine in which said alkyl radical is a tertiary hydrocarbyl radical.

7. A gasoline containing 0.0002 to 0.003 weight percent of a diamine salt of dodecenyl succinic acid and tertiary octylamine.

8. A gasoline containing 0.0002 to 0.003 weight percent of a diamine salt of dodecenyl succinic acid and tertiary butylamine.

References Cited by the Examiner UNITED STATES PATENTS 2,490,744 12/1949 Trigg et al 25234 2,588,412 3/1952 Rocchini 25234 X 2,917,378 12/1959 Vitalis 4456 3,035,907 5/1962 Halter et al. 44 7l 3,039,861 6/1962 Andress et al 4456 3,055,746 9/1962 Eckert 4456 OTHER REFERENCES Kalichevsky et al., Petroleum Refining With Chemicals, 1956, page 480, New York.

DANIEL E. ,WYMAN, Primary Examiner.

C. THOMAS, J. E. DEMPSEY, Assistant Examiners. 

1. A GASOLINE CONTAINING 0.0002 TO 0.0003 WEIGHT PERCENT OF A DIAMINE SALT OF AN ALKENYL SUCCINIC ACID WHEREIN THE ALKENYL GROUP IS C3 TO C24 AND A C4 TO C10 PRIMARY ALKYLAMINE IN WHICH SAID ALKYL RADICAL IS A TERTIARY HYDROCARBYL RADICAL, SAID SALT CONTAINING A TOTAL OF 15 TO 48 CARBON ATOMS, AND IMPARTING IMPROVED ANTI-STALLING, ANTIICING PROPERTIES TO SAID GASOLINE. 